This invention relates to a polymeric material and particularly, although not exclusively, relates to a polyaryletherketone, especially to polyetheretherketone.
The thermoplastic polyaryletherketone polyetheretherketone has been known for over twenty years. EP0001879B (Imperial Chemical Industries) describes its preparation and use and states that, to be useful, polyaryletherketones must have an inherent viscosity (IV) of at least 0.7 dlg−1 (which corresponds to a reduced viscosity (RV) of at least 0.8 dlg−1) measured according to the method described in EP 0001879B. It is stated that, if the IV is less than 0.7 dlg−1, polymers prepared are not tough but are brittle.
Consequently, whilst polymers of IV less than 0.7 dlg−1 have been prepared none is commercially available and none has been used to manufacture components by, for example, injection moulding or extrusion.
For many years, Imperial Chemical Industries and its successor in title, Victrex Plc, were the sole manufacturers of polyetheretherketone. In view of the aforementioned companies' accepted understanding as regards the necessity for any useful polymer to have an IV of at least 0.7 dlg−1, the companies' lowest viscosity polyetheretherketone made commercially available had an MV of 0.15 kNsm−2 (Victrex PEEK (Trade mark) 150) which corresponds to an IV of 0.755 dlg−1). The company also sells two higher viscosity materials, namely a medium viscosity grade (Victrex PEEK 380 having an MV of 0.38 kNsm−2) and a standard viscosity grade (Victrex PEEK 450 having an MV of 0.45 kNsm−2).
Since EP0001879B expired other companies have made polyetheretherketone. For example U.S. Pat. No. 6,566,484 B2 (Gharda Chemicals) describes the preparation of a melt processable polyetheretherketone polymer. The document describes preparation of a range of polymers having different IVs, but there is no suggestion that polymers having an IV of less than 0.7 may have any advantageous properties or commercial use. Gharda Chemicals manufactures and sells polyetheretherketones; its lowest viscosity grade is referred to as grade 5600 which is said to have Melt Flow Rate (MFR) in the range 30-40 cc/10 minutes. This grade has an IV/MV which is substantially the same as that of Victrex PEEK 150 referred to above. The company also sells Grades 5400 and 5300 which have substantially the same IV/MV as Victrex PEEK grades 380 and 450 respectively.
It appears to have been accepted for many years in the area of polyaryletherketones especially as regards polyetheretherketone (which is by far the predominant commercially available polyaryletherketone), that polymers having an IV of less than 0.7 dlg−1 are of no commercial use. However, the present invention is based on a surprising discovery that such polymers have useful properties and that the long accepted statements in EP0001879B are inaccurate. In particular, it is believed that the test for toughness described in EP0001879B may not be an accurate predictor of the properties and/or usefulness of polyaryletherketone polymers.
It is an object of the present invention to provide polyaryletherketone polymers which have advantageous and useful properties.
According to a first aspect of the present invention, there is provided a pack comprising a polymeric material having a melt viscosity (MV) in the range 0.05 to 0.12 kNsm−2 wherein said polymeric material is of a type which includes:
(a) phenyl moieties;
(b) carbonyl moieties; and
(c) ether moieties.
MV is suitably measured using capillary rheometry operating at 400° C. at a shear rate of 1000 s−1 using a tungsten carbide die, 0.5×3.175 mm.
Although the invention is described in terms of MV this may be equated approximately to IV (measured as described in EP0001879B) in accordance with FIG. 1 hereinafter.
It has surprisingly been found that, whilst the viscosity of the polymeric material is significantly less than that of the lowest viscosity commercially available polyaryletherketone, the polymeric material has mechanical properties which are similar to commercially available Victrex PEEK 150. Advantageously, the lower viscosity may enable the polymeric material to be used in applications, for example for highly filled composite materials and/or in injection moulding or extruding components having relatively thin walls, where higher viscosity (e.g. PEEK 150) material could not be used.
Said polymeric material suitably has an MV of 0.06 kNsm−2, preferably has an MV of at least 0.07 kNsm−2, more preferably at least 0.08 kNsm−2.
Said polymeric material may have an MV of less than 0.11 kNsm−2, preferably less than 0.10 kNsm−2.
Said polymeric material may have an MV in the range 0.07 to 0.12 kNsm−2, preferably in the range 0.08 to 0.11 kNsm−2, more preferably in the range 0.08 to 0.10 kNsm−2.
Said polymeric material preferably has an MV in the range 0.07 to 0.10 kNsm−2, more preferably in the range 0.08 to 0.10 kNsm−2.
Said polymeric material may have a tensile strength, measured in accordance with ASTM D790 of at least 80 MPa. The tensile strength is preferably in the range 80-110 MPa, more preferably in the range 80-100 MPa.
Said polymeric material may have a flexural strength, measured in accordance with ASTM D790 of at least 145 MPa. The flexural strength is preferably in the range 145-180 MPa, more preferably in the range 145-165 MPa.
Said polymeric material may have a flexural modulus, measured in accordance with ASTM D790, of at least 3.5 GPa. The flexural modulus is preferably in the range 3.5-4.5 GPa, more preferably in the range 3.5-4.1 GPa.
Said pack may include at least 1 kg, suitably at least 5 kg, preferably at least 10 kg, more preferably at least 14 kg of material of which at least a part is made up of a said polymeric material. Said pack may include 1000 kg or less, preferably 500 kg or less of said material. Preferred packs include 10 to 500 kg of said material.
Said pack may include a composite material as described hereinafter which includes a said polymeric material.
Said pack may include at least 1 kg, suitably at least 5 kg, preferably at least 10 kg, more preferably at least 14 kg of a said polymeric material as described. Said pack may include 1000 kg or less, preferably 500 kg or less of said polymeric material. Preferred packs include 10 to 500 kg of a said polymeric material.
Material in said pack (e.g. a composite material or a said polymeric material per se) may be in powder or granular form.
Said pack may comprise packaging material (which is intended to be discarded or re-used) and a desired material (e.g. a composite material and/or a said polymeric material). Said packaging material preferably substantially fully encloses said desired material. Said packaging material may comprise a first receptacle, for example a flexible receptacle such as a plastics bag in which said desired material is arranged. The first receptacle may be contained within a second receptacle for example in a box such as a cardboard box.
Said desired material in said pack may comprise at least 90 wt % of a said polymeric material and preferably consists essentially of a said polymeric material.
Preferably, said polymeric material has a moiety of formula
and/or a moiety of formula